1. FIELD OF THE INVENTION
This invention is in the general field of detecting motion and speed of objects under surveillance, when such objects cannot be observed visually and are at a distance from the point of surveillance.
This invention is more particularly directed to the detection of the motion and speed of an automotive vehicle, or other vehicle, under surveillance, wherein a transmitter may be connected to such vehicle.
2. DESCRIPTION OF THE PRIOR ART
There are various means for detecting motion of objects. Under proper circumstances, radar and the like may be utilized to detect the speed of objects or the motion of such objects.
Visual observation can, of course, likewise be used for this purpose.
There are many circumstances, in which radar and the like are ineffective, or unuseable, and, in any event, complex and expensive.
There are some radio devices such as direction finders or the like, when utilized in pairs, which can detect the motion of an object to which a transmitter is attached and by appropriate triangulation the actual speed may sometimes be calculated.
All of the past known methods and apparatus for the determination of speed and motion (except visual observation) are complex and require coordination and expense, as is clear to those skilled in the art.
I have devised a method, and an apparatus for practicing such method, wherein we monitor, in an economical manner, and by a single operator, the motion and speed of an object to which a transmitter is attached. I accomplish this by detecting, remotely, the impedance, and changes thereof, in an antenna attached to such transmitter. It has been known in the past that such conditions as birds perching upon an antenna, and other such disturbances cause changes in the antenna impedance; however, this has always been merely a "problem" which has been the subject of research for the purpose of attempting to eliminate the changes. There is no prior art suggesting or utilizing the impedance changes of antennas for the unique and constructive purpose herein.